random: always fill buffer in get_random_bytes_wait

In the unfortunate event that a developer fails to check the return
value of get_random_bytes_wait, or simply wants to make a "best effort"
attempt, for whatever that's worth, it's much better to still fill the
buffer with _something_ rather than catastrophically failing in the case
of an interruption. This is both a defense in depth measure against
inevitable programming bugs, as well as a means of making the API a bit
more useful.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/include/linux/random.h b/include/linux/random.h
index 4024f7d9c77dfe848de46ee0ea3afea57ad69ec1..2ddf13b4281e14fa0906648f4e0bec0546ac5f29 100644 (file)
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -85,10 +85,8 @@ static inline unsigned long get_random_canary(void)
 static inline int get_random_bytes_wait(void *buf, int nbytes)
 {
        int ret = wait_for_random_bytes();
-       if (unlikely(ret))
-               return ret;
        get_random_bytes(buf, nbytes);
-       return 0;
+       return ret;
 }
 
 #define declare_get_random_var_wait(var) \